In high power gas lasers excitation of the laser can be obtained utilizing an electrical discharge in the laser mixture. Ultraviolet preionization has proved to be effective in achieving pulsed stable electrical glow discharge in high pressure CO.sub.2 laser mixtures. The ultraviolet provides initial electrons in the interelectrode space whereby volume ionization is possible in the presence of an applied electric field. The ultraviolet source for preionization in the laser mixture is generally provided by sparks of various design. In situations where there is no ultraviolet preionization the breakdown of the gas may procede by random cosmic ray event to provide electrons in a local region, or by electron emission at field enhancement sites of macroprotrusion on electrode surfaces. These forms of breakdown may easily lead to undesirable electron multiplication in a local region and development into arc channels. Ultraviolet preionization to provide a stable electrical glow discharge overcomes or reduces these problems.